This patch adds AArch32 support to cpu ops, context management,
per-cpu data and spinlock libraries. The `entrypoint_info`
structure is modified to add support for AArch32 register
arguments. The CPU operations for AEM generic cpu in AArch32
mode is also added.

Change-Id: I1e52e79f498661d8f31f1e7b3a29e222bc7a4483